Grinding machine



June 16, 1942. A, w, MALL 1 2,286,293

GRINDING MACHINE Filed March-4, 1940 3 Sheets-Sheet 1 5 Fiel INVENTIII'RQM WM 772 i? BY flaw/m2; ATTORNEY June 1 1942. A. w. MALL 2,286,293

GRINDING MACHINE Filed March 4, 1940 3 Sheets-Sheet 2 Fie.2

/6 i /6 /4 v l4 INVENTIIIR" W Km ATTORNEY June 16, 1942. w, MALL2,286,293

GRINDING MACHINE Filed March 4, 1940 3 Sheets-Sheet 3 512%! I IIAI,

JNVENTUR 4M. Maw." 772412 a&% Jx2z;

ATTORNEY applied to the work as it progresses.

Patented June 16, 1942 UNITED stares earaur OFFICE GRINDING MACHINEArthur William Mall, Flossmoor, Ill.

Application March 4, 1940, Serial No. 322,214

6 Claims.

adaptable to the needs of the grinding industry.

A specific object is to reduce the initial cost of the machine byeliminating frame work for supporting the machine. In my machine themotor itself serves as the basic frame. Brackets are formed integrallywith the end housings of the motor and the wheeled supports are securedto the brackets.

By providing two universally pivotal casters.

at the rear of the machine and one at the front in combination with theprovision of a low center gravity of the entire machine, I obtain thetype of machine which is readily manipulable.

When the operator is grinding terrazzo, for example, his only concern isto keep the grinder Consequently it is desirable to move the grindingspindle about at will. In the operation of my machine any slight pull onthe flexible shaft by the operator will cause the machine to tag alongin any direction with the least of effort. The low center of gravityallows the machine to be .jerked about without any fear of its beingtipped over.

Along with the combination of features which assure an easilymanipulable machine, I have provided variable pitched motor andcountershaft pulleys for changing the speeds of the grinding spindlewhereby the machine may be adapted toa number of different kinds ofgrinding operations. To facilitate changing or loosening and tighteningof the pulley belt, I have provided a quickly operable eccentric device.

The primary object of my invention is to provide a grinding machinewhich incorporates a combination of features which unite to make themachine readily adaptable to industrial needs.

One of the specific objects is to provide a simple and expedient devicefor loosening and tightening the pulley belt.

Another object is to provide the machine with a low center of gravity toprevent tipping.

Another object is to provide the machine with universally pivotalwheeled supports so that the machine will tag along after the operator.

Still another object is to provide a bracket member which serves as awrench for changing grinding wheels and which also serves as asupporting hook around which the electrical cord may be wound when themachine is not in use.

Other objects and advantages will be apparent upon reading the followingspecification and the accompanying drawings. forming a part of thespecification, in which:

.Fig. -1 is a side elevation of the machine;

Fig. 2 is a front view;

Fig. 3 is a fragmentarysectional view of the countershaft housing; and

Fig. 4 is a sectional view taken on line 4-4 of Fig. 3.

In the preferred embodiment of my invention I have shown a motor I of H.P. capacity,

capable of 2 H. P. momentary overload capacity.

Avariable pitch motorpulley 2 drives the countershaft pulley 3 by meansof belt 28. I have provided a flexible shaft take-.ofi 4 from thecountershaft pulley and a grinding wheel spindle .5 driven by thefiexibleshaft 4. Suitable guards 6 and 1 are provided for each pulley.

The motor I is .provided at each end with end bells 8 and 9. A boss I0is formed integrally with the end bell 8. A bracket H is secured to theboss [0 by being bolted thereto. A universally pivotal caster I2 isfastened to the forward end of the bracket ll. Support arms l3 areformed integrally with the end bell 9 and are provided with hubs M towhich are mounted a pair of universally pivotal casters IS.

The arms [3 are spaced well apart providing .a sufficient area ofsupport to assure against the machine tipping over sideways.

The motor I which forms the major portion of the weight of the :entiremachine is disposed centrally between the three casters to assure a Wellbalanced machine. The center of gravity of the machine is located at a.point centrally between the three casters and closely adjacent thefloor level. Thus it can be seen that tipping of the machine is rarelypossible. This is an important feature of the invention as the machineis of the type that is dragged about somewhat carelessly by theoperator.

By using three casters instead of four a tricornered support for themachine is obtained. This assures that the "machine is more readilyadaptable to tag along after the operator regardless of which directionhe pulls on the flexible shaft. The casters are universally pivotal soas to cause the machine to readily follow the direction of the operatorspull.

The support arms l3 have bosses 16 formed integrally therewith. Thesebosses are bored to receive the ends of a U-shaped handle I! which isused to push the machine about from one grinding operation to another.In the upper region of the handle H a spindle wrench I8 is securedthereto, thereby assuring that a wrench will always be available forunloosening the spindle nut when it is desired to change grindingwheels. A hook I9 is also secured to the handle H in the upper regionthereof and serves as a means for supporting the spindle when not inuse.

When the machine is not in use the electrical cord 20 is wrapped aboutthe handle I! and supported by the wrench l8 and the hook IS. A tool box2| is supported immediately above the motor by means of the brackets 22,23, and 24. The tool box has upwardly extending and inwardly convergingside walls 25.

A boss 26 is formed integrally with the motor end bell 8 and supportsthe upright 21.

Referring particularly to Figs. 3 and 4 I have provided a novel meansfor loosening and tightening the pulley belt 28. Formed integrally withthe upright 21 at the upper end thereof is a cylindrical ring membergenerally referred to as 30. The countershaft 3| to which thecountershaft pulley 3 is secured, is journalled in bearings 32 and 33within the countershaft housing 34. The bearings 32 and 33 are spaced bythe sleeve 46 and a cap nut 41 retains the bearings 32 and 33 inposition. A drive nut 48 is adapted to receive the threaded tip of theflexible drive core (not shown). Secured to the countershaft housing 34preferably by welding thereto is an eccentric annular flange 35rotatably journaled in a cylindrical recession 36 Within the ring member30. The inner face of the flange 35 abuts the annular shoulder 31. Asecond cylindrical recession 38 in the ring 30 is adapted to receive thehead 39 of a bolt 40. The head 39 abuts the annular shoulder 4|. Thebolt 43 is journaled through a bore 42 in the eccentric flange 35. Areduced region in the ring 30 forms a collar 60 defined between theshoulders 31 and 4|. The bolt 40 is milled at 43 so as to fit snuglyagainst the inner surface of the collar 60. Thus when the nut 44 isloosened or tightened the bolt 49 will not rotate along with the nut.

Thus it can be seen that when it is desired to change the pulley belt 28from one groove to another or when it is desired to loosen or tightenthe belt 28, the nut 44 is loosened. The eccentric flange 35 is thenfree to be rotated within the cylindrical recession 36. The operatorgrasps the countershaft housing 34, to which the eccentric flange 35 iswelded, and turns it so as to rotate the eccentric flange 35. It can beseen that this changes the position of the countershaft pulley 3relative to the motor pulley 2, either increasing or decreasing thedistance between the axes of the two pulleys (whichever is desired).When the desired loosening or tightening of the belt 23 is obtained, thecountershaft housing 34 and eccentric flange 35 are manually held in thedesired position until the nut 44 is tightened again. When the nut 44 istightened, this locks the inner face of the eccentric flange 35 againstthe shoulder 31 thereby retaining the countershaft pulley 3 in itsselected adjusted position.

Referring to Fig. 2 a switch 50 for starting and shutting off the motorI is secured to the motor housing and has an electrical conductor cable20 with .a plug-in Having thus described my invention what I claim is:

1. A grinding machine comprising movable supporting means, a grindingtool, a motor, a motor shaft, an upright secured to the motor, a hubportion at the upper end of the upright, a bore in said hub portion, acountershaft housing journaled in the bore, a countershaft within thehousing and operatively connected to the grinding tool, a pulley securedto the countershaft, a second pulley secured to the motor shaft, a belttrained about the pulleys, means for adjusting the tension of the beltrelative to the pulleys, said means including a ring rotatably journaledin the hub bore, an eccentric bore in said ring, said countershafthousing being journaled in the eccentric bore and secured to the ring soas to be rotatable therewith, whereby the adjustment of the belt tensionis obtained by manually rotating the countershaft housing and theeccentrically bored ring until the desired tension is obtained, andmeans for maintaining the adjusted tension of the belt, said meansincluding a bolt extending through the eccentric ring for clamping thering in a fixed position within the bore of the upright.

2. A grinding machine as defined in claim 1 wherein there is a flangedregion within the hub bore against which the head of the bolt abuts soso as to clamp the ring in a fixed position within the hub bore of theupright.

3. A countershaft pulley drive device comprising spaced pulleys, asupport member for one of the pulleys, a belt trained about the pulleys,a pulley shaft extending through the support member and secured to thepulley for rotation therewith, means for adjusting the tension of thebelt relative to the pulleys, said means including an eccentricallybored ring rotatably mounted in said support member, said pulley shaftextending through the eccentric bore, a bolt hole, an annular shoulderin said support member, whereby the bolt may be tightened against saidshoulder.

4. A countershaft pulley drive apparatus, comprising spaced pulleys, asupport member for one of the pulleys, a belt trained about the pulleys,a

pulley shaft secured to the pulley for rotation V therewith, means foradjusting the tension of the belt relative to the pulleys, said meansincluding a ring rotatably mounted in the support member, an eccentricbore in said ring, said pulley shaft extending through the eccentricbore, and means for maintaining the adjusted tension of the belt, saidlast means including a bolt extending through the eccentric ring forclamping the ring in a fixed position relative to the support member.

5. A countershaft pulley drive apparatus, comprising spaced pulleys, asupport member for one of the pulleys, a belt trained about the pulleys,a pulley shaft secured to the pulley for rotation therewith, means foradjusting the tension of the belt relative to the pulleys, said meansincluding a ring rotatably mounted in the support member, an eccentricbore in said ring, said pulley shaft extendingthrough the eccentricbore, and means for maintaining the adjusted tension of the belt, saidlast means including a bolt extending through the ring, and an annularshoulder in the support member, said bolt being adapted to clamp thering against the annular shoulder.

6. A countershaft pulley drive apparatus, comprising spaced pulleys, asupport member for one of the pulleys, a belt trained about the pulleys,a

for maintaining the adjusted tension of the belt, said last meansincluding a clamping member having engagement with the ring and theannular shoulder for urging the ring against the shoulder to preventrotation of the ring relative to the shoulder.

ARTHUR WILLIAM MALL.

